The present invention generally relates to the field of automotive systems, and particularly to power window systems.
In a power window system, it is desirable to precisely control the motor that causes the window to move, for example upwards or downwards. For a given motor and characteristic parameters such as the motor torque constant (Kt) or the armature constant (Ka), a given input current will cause the rotor to rotate a predetermined amount of angular rotation in a given time. For a consistent system of units, the motor torque constant and the armature constant are equivalent. With knowledge of the torque parameter constant for a given motor, the time and current required to cause the motor to turn a given amount of angular rotation, and thus the position of the window, can be determined. However, the motor torque parameter value for a given motor will change with age and operating conditions such as applied voltage and temperature. It would therefor be highly desirable to provide a system and a method by which the position of a power window may be determined and controlled with a greater precision by accurately determining the motor torque value of the motor utilized to drive the window.
The present invention is directed to a system and method for operating a power window system by using a torque parameter value of the motor of the power window system. A table of torque parameter values for corresponding operating conditions is generated, and the motor is operated according the table of operating conditions. The table of torque parameter values and operating conditions may be updated to reflect any changes in the characteristics of the motor over time, and the motor may then be operated according to the updated table values.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.